1. Field of the Invention
The present invention relates generally to an apparatus and a method for efficiently transmitting emergency information in a wireless charging network, and more particularly, to a wireless power transmitter, a wireless power receiver, and a method for transmitting emergency information in a wireless charging network.
2. Description of the Related Art
Wireless charging techniques use wireless power transmission and reception to automatically charge a battery of an electronic device, e.g., a mobile phone, when the electronic device is located within a predetermined distance of a charging device, e.g., put on a charging pad, without physically connecting the electronic device to a conventional charger.
The wireless charging techniques are broadly categorized into an electromagnetic induction type using coils, a resonance type using a resonance phenomenon, and a Radio Frequency (RF)/Microwave radiation type, which converts electrical energy into microwaves for transmission.
The electromagnetic induction technique transmits power between a primary coil and a secondary coil. More specifically, when moving a magnet around a coil, a current is induced and electricity is generated. That is, a transmission end generates a magnetic field and a reception end generates energy on behalf of the magnet, which is commonly referred to as an electromagnetic induction phenomenon.
The resonance technique wirelessly transmits power using a resonance-type power transmission principle over greater distances than the electromagnetic induction technique. Basically, electromagnetic waves are resonated containing electric energy, which is directly transferred only to a device having a matching resonance frequency, and any unused portion is reabsorbed into an electromagnetic field instead of spreading in the air.
Although various studies have been performed on the wireless charging techniques, when emergency situations occur in the wireless power receiver (or Power Reception Unit (PRU)), such as an over voltage, an over current, an over temperature, or a system error, the wireless power receiver should transmit emergency situation information to the wireless power transmitter (or Power Transmission Unit (PTU)). However, in conventional signal transmission protocols, no method has been proposed for the wireless power receiver to transmit the emergency situation information to the wireless power transmitter.